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Abstract

Background Adenosine is the preferred hyperemic agent for fractional flow reserve (FFR) measurements in patients with coronary artery stenosis, but is may not produce maximal hyperemia. Uridine triphosphate (UTP) is a selective P2Y2 receptor agonist and a potent hyperemic agent in the peripheral circulation, but its role for measuring coronary FFR is unknown. We therefore tested whether continuous intracoronary (IC) UTP reduced FFR more than both continuous IC and intravenous (IV) adenosine infusion. Furthermore, we also evaluated differences in adverse effects.

Methods and Results FFR was measured in 25 patients during steady state IC or IV infusions. Continuous IC infusion was achieved by using a micro-catheter in the ostium of the investigated artery. We infused eight incremental doses of IC UTP and adenosine (20, 40, 60, 80, 160, 240, 320 and 640 µg/min) and standard intravenous IV adenosine infusion (140µg/kg/min) in a randomized order. Patients were questioned about adverse effects during each infusion. IC UTP (FFR=0.62± 0.04) lowered FFR significantly more than both IV adenosine (0.72± 0.05, P=0.02) and IC adenosine (0.68± 0.05, P=0.03). UTP also significantly reduced the adverse effects in comparison to both IV and IC adenosine.

Conclusions IC UTP infusion induces more hyperemia and thus reduces FFR more than both IC and IV adenosine.UTP infusion is also associated with significantly fewer adverse effects than adenosine. Therefore adenosine does not seem to be the optimal agent for FFR measurements and UTP may prove to be an ideal replacement for FFR measurements in the catheterization laboratory.